Porphyra umbilicalis (laver) belongs to an ancient group of red algae (Bangiophyceae), is harvested for human food, and thrives in the harsh conditions of the upper intertidal zone. Here we present the 87.7-Mbp haploid Porphyra genome (65.8% G + C content, 13,125 gene loci) and elucidate traits that inform our understanding of the biology of red algae as one of the few multicellular eukaryotic lineages. Novel features of the Porphyra genome shared by other red algae relate to the cytoskeleton, calcium signaling, the cell cycle, and stress-tolerance mechanisms including photoprotection. Cytoskeletal motor proteins in Porphyra are restricted to a small set of kinesins that appear to be the only universal cytoskeletal motors within the red algae. Dynein motors are absent, and most red algae, including Porphyra, lack myosin. This surprisingly minimal cytoskeleton offers a potential explanation for why red algal cells and multicellular structures are more limited in size than in most multicellular lineages. Additional discoveries further relating to the stress tolerance of bangiophytes include ancestral enzymes for sulfation of the hydrophilic galactan-rich cell wall, evidence for mannan synthesis that originated before the divergence of green and red algae, and a high capacity for nutrient uptake. Our analyses provide a comprehensive understanding of the red algae, which are both commercially important and have played a major role in the evolution of other algal groups through secondary endosymbioses.cytoskeleton | calcium-signaling | carbohydrate-active enzymes | stress tolerance | vitamin B 12T he red algae are one of the founding groups of photosynthetic eukaryotes (Archaeplastida) and among the few multicellular lineages within Eukarya. A red algal plastid, acquired through secondary endosymbiosis, supports carbon fixation, fatty acid synthesis, and other metabolic needs in many other algal groups in ways that are consequential. For example, diatoms and haptophytes have strong biogeochemical effects; apicomplexans cause human disease (e.g., malaria); and dinoflagellates include both coral symbionts and toxin-producing "red tides" (1). The evolutionary processes that produced the Archaeplastida and secondary algal lineages remain under investigation (2-5), but it is clear that both nuclear and plastid genes from the ancestral red algae have contributed dramatically to broader eukaryotic evolution and diversity. Consequently, the imprint of red algal metabolism on the Earth's climate system, aquatic foodwebs, and
The origin of the red algae has remained an enigma. Historically the Rhodophyta were classified first as plants and later as the most ancient eukaryotic organisms. Recent molecular studies have indicated similarities between red and green plastids, which suggest that there was a single endosymbiotic origin for these organelles in a common ancestor of the rhodophytes and green plants. Previous efforts to confirm or reject this effort by analyses of nuclear DNA have been inconclusive; thus, additional molecular markers are needed to establish the relationship between the host cell lineages, independent of the evolutionary history of their plastids. To furnish such a data set we have sequenced the largest subunit of RNA polymerase II from two red algae, a green alga and a relatively derived amoeboid protist. Phylogenetic analyses provide strong statistical support for an early evolutionary emergence of the Rhodophyta that preceded the origin of the line that led to plants, animals, and fungi. These data, which are congruent with results from extensive analyses of nuclear rDNA, argue for a reexamination of current models of plastid evolution.
Objective-Based on the reported association between cytokines with depression and suicide, and evidence of increased markers of inflammation in the brain of suicide victims, the present study examined the expression of cytokines in the orbitofrontal cortex of suicide victims.Method-In a postmortem sample obtained from the Brodman area 11 of suicides (n = 34) and controls (n = 17), real-time RT-PCR was used to compare the expression of mRNA species for tumor necrosis factor-a (TNF-α), interleukin (IL)-1β, 4, 5, 6, and 13.Results-Increased expression of IL-4 was found in women suicide victims and IL-13 in men suicide victims. Elevated but not significant cytokine expression was also observed for TNF-α in women suicide victims. • Limited information on psychiatric diagnoses and blood toxicology in the suicide group. Conclusion-To NIH Public Access
Chromist algae include diverse photosynthetic organisms of great ecological and social importance. Despite vigorous research efforts, a clear understanding of how various chromists acquired photosynthetic organelles has been complicated by conflicting phylogenetic results, along with an undetermined number and pattern of endosymbioses, and the horizontal movement of genes that accompany them. We apply novel statistical approaches to assess impacts of endosymbiotic gene transfer on three principal chromist groups at the heart of long-standing controversies. Our results provide robust support for acquisitions of photosynthesis through serial endosymbioses, beginning with the adoption of a red alga by cryptophytes, then a cryptophyte by the ancestor of ochrophytes, and finally an ochrophyte by the ancestor of haptophytes. Resolution of how chromist algae are related through endosymbioses provides a framework for unravelling the further reticulate history of red algal-derived plastids, and for clarifying evolutionary processes that gave rise to eukaryotic photosynthetic diversity.
A total of 28,432 unique contigs (25,371 in consensus contigs and 3,061 as singletons) were assembled from all 268,786 cotton ESTs currently available. Several in silico approaches [comparative genomics, Blast, Gene Ontology (GO) analysis, and pathway enrichment by Kyoto Encyclopedia of Genes and Genomes (KEGG)] were employed to investigate global functions of the cotton transcriptome. Cotton EST contigs were clustered into 5,461 groups with a maximum cluster size of 196 members. A total of 27,956 indel mutants and 149,616 single nucleotide polymorphisms (SNPs) were identified from consensus contigs. Interestingly, many contigs with significantly high frequencies of indels or SNPs encode transcription factors and protein kinases. In a comparison with six model plant species, cotton ESTs show the highest overall similarity to grape. A total of 87 cotton miRNAs were identified; 59 of these have not been reported previously from experimental or bioinformatics investigations. We also predicted 3,260 genes as miRNAs targets, which are associated with multiple biological functions, including stress response, metabolism, hormone signal transduction and fiber development. We identified 151 and 4,214 EST-simple sequence repeats (SSRs) from contigs and raw ESTs respectively. To make these data widely available, and to facilitate access to EST-related genetic information, we integrated our results into a comprehensive, fully downloadable web-based cotton EST database (www.leonxie.com).
Phylogenetic analyses of ribosomal RNA genes have become widely accepted as a framework for understanding broad-scale eukaryotic evolution. Nevertheless, conflicts exist between the phylogenetic placement of certain taxa in rDNA trees and their expected position based on fossils, cytology, or protein-encoding gene sequences. For example, pelobiont amoebae appear to be an ancient group based on cytologic features, but they are not among the early eukaryotic brances in rDNA analyses. In this report, the derived position of pelobionts in rDNA trees is shown to be unreliable and likely due to long-branch attraction among more deeply branching sequences. All sequences that branch near the base of the tree suffer from relatively high apparent substitution rates and exhibit greater variation in ssu rDNA sequence length. Moreover, the order of the branches leading from the root of the eukaryotic tree to the base of the so-called "crown taxa" is consistent with a sequential attachment, due to "long-branch" effects, of sequences with increasing rates of evolution. These results suggest that the basal eurkaryotic topology drawn from rDNA analyses may be, in reality, an artifact of variation in the rate of molecular evolution among eukaryotic taxa.
In model eukaryotes, the C-terminal domain (CTD) of the largest subunit of DNA-dependent RNA polymerase II (RNAP II) is composed of tandemly repeated heptads with the consensus sequence YSPTSPS. The core motif and tandem structure generally are conserved across model taxa, including animals, yeasts and higher plants. Broader investigations revealed that CTDs of many organisms deviate substantially from this canonical structure; however, limited sampling made it difficult to determine whether disordered sequences reflect the CTD's ancestral state or degeneration from ancestral repetitive structures. Therefore, we undertook, to our knowledge, the broadest investigation to date of the evolution of the RNAP II CTD across eukaryotic diversity. Our results indicate that a tandemly repeated CTD existed in the ancestors of each major taxon, and that degeneration and reinvention of this ordered structure are common features of CTD evolution. Lineage-specific CTD modifications appear to be associated with greater developmental complexity in multicellular organisms, a pattern taken to an extreme in fungi and red algae, in which the CTD has undergone dramatic to complete alteration during the transition from unicellular to developmentally complex forms. Overall, loss and reinvention of repeats have punctuated CTD evolution, occurring independently and sometimes repeatedly in various groups.has a unique C-terminal domain (CTD) that, in its canonical form, is composed of tandemly repeated heptapeptides with the consensus YSPTSPS. It has been more than a quarter century since the CTD was first described in yeast (1), in which global functions and constraints on its evolution are most thoroughly understood (2, 3). In yeast and animals, the CTD mainly functions as a docking platform to recruit transcription and processing factors at appropriate stages of the transcription cycle (4, 5). Research to date has revealed that CTD-associated factors have a variety of functions, such as mRNA 5′ capping and 3′ processing, pre-mRNA splicing, histone modification, and snRNA processing (6-8). Moreover, the CTD uses different codes to recruit different protein factors (9-11). Reversible phosphorylation of Ser2 and Ser5 residues are the primary CTD codes, and are crucial for regulating transcription and binding mRNA processing factors (12); the major kinases responsible for these phosphorylations are conserved from yeast to metazoans (13). The CTD adopts additional modifications to enrich its functions, including Tyr1 (14), Ser7 (15), and Thr4 phosphorylations (16, 17), as well as cis/trans isomerization of Pro3 and Pro6 (18).Despite its essential nature and the conservation of multiple core functions, when and in what form the CTD originated remains unclear, as do reasons for the remarkable diversity in CTD sequences and structures across eukaryotic organisms. The last major explicitly phylogenetic treatment of broad-scale CTD evolution was published more than 10 y ago and suggested the presence of a "CTD clade," all descended from a common...
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